Medical procedures often require that a biomedical specimen be coupled to a carrier. For example, medical devices such as stents, markers or sleeves are generally coupled to catheters or balloons that deliver the device to a target area where the device is deployed by uncoupling the device from the carrier.
More particularly, a stent may be coupled to a catheter having a balloon at the distal end by crimping the stent on the balloon in deflated condition. The catheter is then introduced in a vessel of a patient and, when a target location is reached, the balloon is inflated, causing the stent to expand and to support the wall of the vessel as desired. Alternatively, a self-expanding stent may be coupled to the distal end of a catheter and be covered by a sheath. The catheter is then introduced in a patient's vessel and, when the target location is reached, the sheath is retracted, enabling the stent to self-expand and scaffold the vessel wall.
In this respect, it is of great importance that the medical device be properly coupled to the carrier, so to avoid the decoupling of the device from the carrier at an undesired location. In the case of a balloon-expanded stent, the stent must be coupled to the balloon and to the catheter with contact force sufficient to create an interference that will prevent the stent from sliding off the balloon while the balloon travels in the patient's vessels along its path to the target location, especially considering that friction with the vessel walls or bends in the vessel system are prone to induce such a decoupling.
An undesired decoupling of the medical device from the carrier would not only render the procedure difficult or impossible to perform, but also lodge the stent at an improper location and require a surgical procedure for removing the misplaced stent.
Known methods and systems for measuring the retention force of a biomedical specimen on a carrier are based on mechanical principles. Such methods and systems are based on mechanically impacting the structure to be measured, thereby negatively affecting the mechanical integrity of the system and a proper reading of the values to be measured. One such mechanical test is a tensile pull test, which determines the mechanical force required to pull the stent off the delivery balloon. Another such test is compressive in nature. These types of mechanical tests are described, for example, in Example 2 of U.S. Pat. No. 6,682,553 and in Example 1 of U.S. Pat. No. 6,673,102.